I am going to install a new hot tub outside under a covered deck. I live in a village, where we have municipal service (commonly referred to as, "village electric") The village electric service is slightly less expensive than the major national service providers. But someone told me that if I hook up the hot tub using a 220 line, then the monthly bill will be less than if I used a standard 110 outlet connection. I have the capacity in my panel box to accommodate the 220 line, or I can use a 110 connecting cord and plug the tub into an outlet on the deck. Any thoughts on whether the 220 hookup would result in a lower monthly bill?

I'm not sure if this is more of an HVAC or electrical questions so I'm sorry if this is in the wrong forum. I am doing some work on my basement. The one wall is unfinished on the one side and there is an air return in the plenum space in the wall. I took the temporary metal panel off that closes the plenum space on the unfinished side and there was a romex cable running through the studs horizontally across the vertical plenum space. The holes in the studs that go through the plenum space are not sealed or anything. The romex cable is NM-B. I was looking at the NEC to make sure it was up to code because I didn't think the cable was plenum rated but the language is very verbose and wanted to get a more layman's explanation. I can give more details if needed but hopefully I included all the necessary details. Is this ok or does something need to be done?